I had unprotected sex with my boyfriend 12 days after my menstrual cycle!two weeks after my nipples became sore.could I be pregnant already?

Yes! Depending on the cycle of your period, 12-14 days after the first day of your last period is your most fertile time. You ovulate around that time. Which means at that time you could have very well become pregnant as sperm can live up to 5 days in a woman's vagina. Two weeks is never too early for pregnancy signs. Some woman get them at 1 week. Have you had any spotting? Morning sickness? Keep in mind, not all woman get spotting, and only 50% of woman get morning sickness. Have you taken a test? 2 weeks after a missed period, you should be able to tell by a HPT. Depending on your HCG level (pregnancy hormone) it may not be strong enough. The best thing to do is to take a test, if positive. CONGRATS! If negative wait another week or two, if negative and still no period go to the dr and ask for a blood test as blood tests determine accuracy better than any urine test.